This invention relates to means for transporting tools and instruments to locations inside pipes, well holes and other such passageways, and to means for providing power or data connections to these tools.
There are many applications in which it necessary to transport a tool or instrument far into a narrow passageway such as an oil well hole, a pipeline or a waterline, and in which an energy or information transmitting conduit such as an electrical cable is connected to the tool and extends outside the passageway. The passageways may be not be vertical, and they may curve along their length. Therefore the means for moving the tool will have to be able to exert a lengthwise force on the tool, both pushing it into and pulling it out of the passageway. The means must also be flexible enough to accommodate the passageway curves.
A method typically used in oil and gas wells is to connect the tool to flexible tubing, with the conduit inside the tubing. The conduit is housed in a flexible polymer rod, the rod in turn being centered inside the tubing.
Such a flexible tubing system has disadvantages which include high manufacturing costs and problems related to the strength of the flexible tubing. The tubing can be crushed or its inner channel pinched off if bent too sharply. Both crushing and pinching off can sever the conduit. The flexible tubing has limited axial strength. Tubing often has a short stress cycle life, so it can be used for only a few well servicings. The conduit cannot be accessed for inspection or repair without cutting into the tubing.
There are also applications in which is desirable to have a conduit connected to equipment far into the passageway, while also having a rigid connection transmitting the force required to operate the equipment. An example is a downhole oil well pump, in which a downhole piston is connected to drive gear at the surface by a solid metal sucker rod. The surface gear moves the downhole piston up and down through the sucker rod. It would be useful to monitor pressure or other properties at the downhole piston while the pump is operating. Another example is pipe or tubing that rotates a tool, such as a drilling tool, in a passageway, for which it would be useful to monitor properties at the tool while it is rotating.
This invention seeks to overcome problems with the prior art. According to an aspect of the invention, there is provided a device for moving equipment. The device comprises a rod having a groove set in it extending along the length of the rod. A groove extends along the rod and inward into the rod from the rod outer surface. A transmission conduit extends along the rod within the groove. According to further aspects of the invention, the groove is wider deeper in the groove than at the rod outer surface and the groove width at the rod outer surface is smaller than the diameter of the transmission conduit.
The transmission conduit should be sealed in the groove against fluid flow along the groove between the transmission conduit and the groove in any case where pressure may be a problem. Preferably, the transmission conduit is sealed in the groove by a sealant, and the sealant occupies all of the groove that is not occupied by the transmission conduit.
The device is typically used in combination with a rod actuator coupled to the rod for moving and positioning the rod. The rod actuator may be a rod injector or rod rotator.
According to a further aspect of the invention, the rod has an elongated cross-section defining a curved rod outer surface, and the groove is located where the longest cross-section diameter intersects the surface. The rod may have a cross-section forming the shape of an ellipse having a major axis, and the groove is located where the major axis intersects the rod surface.
According to a further aspect of the invention, there is provided apparatus for use in a well, the apparatus comprising a rod having an outer surface, the rod extending between a first end and a second end, a downhole tool being mounted on the first end of the rod, the second end of the rod being outside the well, a groove along the rod between the first and second ends and extending inward from the rod outer surface, a transmission conduit extending along the rod and sealed within the groove, the transmission conduit being connected to the downhole tool and extending to the second end of the rod, and a rod actuator coupled to the rod for moving the rod and downhole tool in the well.
According to a further aspect of the invention, there is provided a method for installing a transmission conduit in a groove along the length of a rod, the rod having an outer surface and the groove extending inward from the rod outer surface, comprising the steps of:
installing the transmission conduit in the groove from the rod outer surface; and
sealing the rod in the groove.
According to a further aspect of the invention, there is provided the method step of reducing the groove width at the rod outer surface so the transmission conduit is retained in the groove.